Internal function not usually called by users
xy0_root.f(x, y0, SK, par.lme, ...)difference between actual diameter at height x and given
diameter y0
relative height
diameter for which height is required
return of SK_EBLUP_LME.f containing estimated fixed
and the tree specific random effects of the taper model
List of taper model parameters obtained by TapeR_FIT_LME.f
not currently used
Edgar Kublin
used in xy0_SK_EBLUP_LME.f to find the root of taper curve
(i.e. height x) at given diameter y0